I am also really worried they’re going to start making things “touch friendly” now… And we’re going to end up with the MacOS equivalent of Windows 8.

You mean iPadOS?

Plenty of bags could have fit on top of my flat, 4-inch thick electric guitar case.

Because musical instruments are specifically allowed by federal DOT rules?

Specifically: ”A small instrument must be accepted as cabin baggage when it fits safely in an approved overhead or under-seat space and that space is available when you board. Ordinary carry-on size limits aren’t a reason to reject an instrument that meets those storage conditions."

https://www.airtravelquestions.com/tsa-rules/can-you-bring-a-musical-instrument-on-a-plane

And as I said in another comment, laid flat it fit quite easily in the overhead compartment with plenty of room for additional bags. The compartment over my seat was not filled before takeoff and was fully empty when I boarded. It would have been both fine and legal for me to stow it there, but the flight attendants insisted on gate checking it regardless.

It was a flat road case for an electric guitar, on a jumbo jet. There was plenty of space for 3 or 4 carry-ons or backpacks to sit on top of it and the bin in question was not even remotely full at take off.

I was more than once forced to gate check my guitar because the flight attendants didn’t think any of the overhead bins were wide enough for the case. They were plenty wide.

I can confirm this summary is correct. It’s why we sample audio at at least 44.1KHz even though human hearing only goes up to 20KHz

And a good chunk of our buildings, as well.